The EMECAR portable spot-welding unit is the result of several years of experience in the field of low power resistance spot welders. Its compact size and portability make this unit extremely interesting for the sheet-metalworking industry using the resistance welding technique. This unit is comprised of a moveable trolley with pivoting wheels which holds the transformer and the control panel on the top and the water-cooling system on the bottom. The welding gun is connected to the transformer by a very flexible cooled welding cable which allows the gun to be used in difficult work positions. A wide range of arms, electrode holders and electrodes make the whole system very flexible and suitable for all welding conditions. The unit is completely self-contained and only requires connection to the electric mains and to the compressed air outlet. A close loop system together with an integrated air-water heat exchanger provide the welding gun, the welding cable and the transformer group with cooling. Weld gun made of cast aluminum alloy with lever kinematic mechanism that allows considerable electrode force to be developed even with long arms. The arms and the electrodes are easily interchangeable to configure them to different welding conditions. The light weight and ergonomically designed handle allow extreme mobility in all conditions. “MICRO8” weld control board of synchronous type with a diode microprocessor controlled in 5 steps, offers dual program and pulse as standard. 1000Hz control frequency inverter generator for medium frequency transformers. The compact device allows to control the primary current of the power transformer keeping its value constant regardless of the variations in the mains voltage and any thermal and aging drifts of the different components of the system. The working frequency of 1KHz allows to reduce the dimensions of the transformer and to improve the form factor of the output current by reducing the ripple of the current and allowing the creation of more controlled welding points both in terms of time and maximum current. The inverter control board interfaces with the remote unit such as MICRO8 or J-TEK provides the welding parameters and sends error codes to manage diagnostics in the event of anomalies.